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Biomedical subjects

K Walker

Publications and source records attributed to K Walker.

At least 109 records · Page 6Linked to original sources
PubMed1992

Quantification of errors in laboratory reports. A quality improvement study of the College of American Pathologists' Q-Probes program.

Over a 3-month period, 61,496 errors were detected in clinical laboratory reports by 631 participants in the College of American Pathologists' 1990 Q-Probes program. Each error detected was defined as an opportunity for improvement. Almost 4% of the detected errors were attributed to nonlaboratory personnel and approximately 4% (A errors) had a major impact on patient care. Rates of B (serious errors, but unlikely to affect patient care) and C errors (minor clerical errors) were approximately equal. When expressed in terms of measures of laboratory work loads, four of six measures of mean errors were lowest in blood banking, intermediate in chemistry and microbiology, and highest in hematology. Thirteen percent of participants did not have an error detection system in place. We conclude that many errors go undetected, and we recommend that an effective system for error detection in patient reports should be employed in all laboratories.

Blood Banks↗
PubMed1990

Inhibition of protein synthesis by anti-5.8 S rRNA oligodeoxyribonucleotides.

To examine the role of the 5.8 S rRNA in ribosome function, oligodeoxyribonucleotides, complementary to chemically accessible sequences, were incubated with rabbit reticulocyte or wheat germ extracts undergoing protein synthesis in vitro. Significant and reproducible inhibitions were observed with several different oligonucleotides, the most inhibitory being specific for the universally conserved GAAC sequence. Mutant or heterologous sequences were substantially less inhibitory, results which clearly implicate the 5.8 S rRNA in the inhibitory process and are consistent with the possibility that the 5.8 S rRNA plays an important role in the binding of tRNA.

Animals↗
PubMed1990

Termination region in rRNA genes from a eucaryotic thermophile, Thermomyces lanuginosus.

S1 mapping of the termination region in the ribosomal DNA from a thermophilic fungus, Thermomyces lanuginosus, revealed three distinct termini corresponding to the mature 25S rRNA, a precursor that is 19 nucleotides longer and corresponds to the 37S precursor in yeast cells, and a putative termination site at +96 that bears a limited sequence homology with the SalI box of mammalian cells. An estimate of the secondary structure suggested that the three termini are in close proximity, a feature that may be essential to precursor termination and maturation. The results raise questions regarding recently reported relationships between ribosomal DNA termination and spacer enhancer elements in fungi.

Base Sequence↗
PubMed1990

XO/XY mosaicism in phenotypic males.

Eight cases of 45 XO/46 XY mosaicism are described: four were phenotypic males. Karyotyping should be performed more frequently in short boys as growth hormone treatment and testicular biopsy, to screen for carcinoma in situ, are likely to be beneficial.

Adolescent↗
PubMed1990

Radiation and the small intestine. Future perspectives for preventive therapy.

Radiotherapy continues to enjoy a prominent role in the treatment of certain human tumors. Unfortunately, the undesired effect of radiation upon normal intestinal tissue often limits its therapeutic potential. While there is abundant information on the effects of radiation on the morphology of the intestine and on the proliferative process which occurs in the intestinal crypts, there is a paucity of information on the early and late effects of sublethal doses of radiation upon the absorptive functions of the intestine. The intestinal epithelium has a rapid turnover rate and is highly radiosensitive. Radiotherapy for malignant human neoplasms is a relatively safe and effective form of treatment, but it may become limited by its undesired side effects upon the gastrointestinal tract. A variety of clinical tests have been suggested as potential indicators of impending intestinal damage, but there is little information on the time course of radiation damage and the associated impairment of intestinal function. Such basic information is essential to assess early functional changes and to thereby allow for the development of suitable clinical tests to allow for the prediction of impending intestinal damage. Provision of this information to the radiotherapist would permit alterations to the timing or dose schedules of radiotherapy and would allow continued treatment, while avoiding or reducing unwanted side effects. In recent years, there has been extensive research on radiation injury to small intestine. This article will review some of the progress in this field, and will focus on potential future therapy to prevent or treat radiation damage to the intestine. These agents include WR-2721, enprostil, vasopressin, defined-formula diets and alterations in the ratio of dietary polyunsaturated-saturated fatty acids.

Forecasting↗
PubMed1990

Changes in mallard (Anas platyrhynchos) serum chemistry due to age, sex, and reproductive condition.

Selected serum constituents were analyzed from 50 adult mallards (Anas platyrhynchos) of both sexes during several stages of reproduction: pre-egg laying, egg laying, incubating, molting, and postreproductive. Similar assays were conducted on sera from ducklings aged 5 to 58 days. Values for total protein (TPR), albumin (ALB), glucose (GLU), gamma-glutamyl transferase (GGT), calcium (CA), phosphorus (PHOS) and magnesium (MG) differed by sex. When all data were combined and analyzed for sex-related differences within each reproductive condition separately, all assays except lactate dehydrogenase (LD-L), cholinesterase (CHE), alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (CRN) and direct bilirubin (BIDI) differed between sexes during one or more reproductive periods. Each assay showed differences among the various reproductive conditions regardless of gender. The pattern of change differed between sexes. All assays except ALB, GLU, CA and MG showed age-related changes. Lipemia in the sample interfered with all chemistries except TPR, LD-L and CA. Results indicate that when using clinical chemistry as a diagnostic tool in the mallard, age and reproductive condition should be determined in order to compare the data to appropriate control values.

Age Factors↗
PubMed1990

Dietary fat saturation alters diabetic rat brush border membrane phospholipid fatty acid composition.

Alteration in dietary fatty acid composition produces changes in brush border membrane (BBM) fatty acid composition and changes in nutrient transport. Feeding a highly polyunsaturated fatty acid diet (P) reduces glucose uptake in diabetic rats to near control levels, whereas feeding a highly saturated fatty acid diet (S) enhances glucose uptake. Female Wistar rats were placed onto either a P or S diet for 5 weeks, injected with streptozotocin and continued on their respective diets for an additional 3 weeks. BBM were isolated, purified and extracted for analysis of fatty acyl constituents of phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In jejunal and ileal BBM PC and PE, feeding S was associated with a decrease in total omega 6 fatty acids (18:2 omega 6), and an increase in the ratio of monounsaturated/saturated fatty acids as compared with animals fed P. In jejunal BBM PC and PE, the ratio of 18:2 omega 6/20:4 omega 6 was reduced in animals fed S as compared with those fed P. Diabetes was associated with fewer changes in BBM fatty acid composition in animals fed P as compared with those fed S. Feeding P to diabetic animals prevents the changes in BBM fatty acid composition observed when animals are fed S. Alterations in BBM lipid composition may be related to the enhanced permeability to glucose in animals fed S, while the similarity of BBM fatty acid composition in diabetic and control animals fed P may be related to the similar glucose uptake. The mechanisms controlling BBM lipid composition require further investigation, and may be important for the development of nutritional strategies for the control of diabetes.

Animals↗
PubMed1990

Alterations in dietary fatty acid composition alter rat brush border membrane phospholipid fatty acid composition.

Female Wistar rats were fed for 8 weeks a high polyunsaturated fatty acid diet (P) enriched with 18:2w6 and 18:3w3, or a high saturated fatty acid diet (S) enriched with 16:0, 18:0 and 18:1w9. There was a similar jejunal BBM fatty acid profile in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) composition in animals fed P. However, feeding S altered the fatty acid composition of BBM phospholipids: for PC, feeding S increased total monounsaturated fatty acids (e.g. 18:1(9)) and reduced total polyunsaturated fatty acids, especially the total w6 fatty acids. For PE, feeding S increased only the total monounsaturated fatty acids. The ratio of monounsaturated/saturated fatty acids was increased for PC and PE. Fatty acid changes were more pronounced in the jejunal than ileal BBM. It is concluded that alterations in dietary fatty acid saturation: (a) influences intestinal BBM phospholipid fatty acid composition; (b) these changes are quantitatively and qualitatively different for PC and PE; and (c) changes are greater in the proximal than in the distal intestine. It is proposed that the previously reported diet-associated changes in active and passive intestinal transport are due at least in part to these alterations in the fatty acid composition in brush border membrane phospholipids.

Animals↗
PubMed1990

A randomised controlled trial of medroxyprogesterone acetate in mastalgia.

A double-blind crossover study giving 20 mg/day of medroxyprogesterone acetate during the luteal phase was carried out in 26 women with cyclical mastalgia. Symptomatic response to this progestogen supplementation or placebo was assessed objectively by clinical examination and subjectively by linear analogue scales and breast pain charts. No significant relief of pain or tenderness was found on placebo or active treatment, irrespective of treatment order, and breast nodularity was similarly unaltered. No evidence of progesterone deficiency or prolactin abnormality was found. Side-effects were incurred in 11 patients (five on placebo, five on active treatment and one while on both) and were mostly vague premenstrual symptoms. We conclude that the therapeutic response of medroxyprogesterone acetate in cyclical mastalgia is no better than placebo and that progestogen supplementation can no longer be recommended for routine use in the management of breast pain.

Adult↗
PubMed1989

Dietary carbohydrate-to-fat ratio: influence on whole-body nitrogen retention, substrate utilization, and hormone response in healthy male subjects.

The effect of a high-carbohydrate and a high-fat diet on nitrogen retention, substrate utilization, and serum hormone concentrations was assessed in six healthy male subjects. Both diets were fed at a level estimated to provide maintenance and 75% maintenance energy requirements. Urine and feces were collected and analyzed for N and energy content. Anthropometric measurements; fasting and postprandial oxygen consumption; and serum levels of glucose, triglycerides, and metabolic hormones were measured. The high-fat diet increased N retention at both energy levels with significance reached at maintenance energy intakes (p less than 0.05). The high-fat diet resulted in less weight loss (p less than 0.05) at low energy and a consistently lower respiratory quotient (p less than 0.05), indicative of increased fat oxidation. The N sparing effect of the high-fat diet did not appear to be explained by hormone levels observed but may be substrate mediated.

Adult↗
PubMed1989

Lack of protective effect of oral enprostil, a synthetic prostaglandin E2, on intestinal transport and morphology following abdominal irradiation in the rat.

Previous studies have demonstrated that abdominal irradiation alters intestinal uptake of nutrients. The purpose of this study was to determine the effect of an orally administered synthetic prostaglandin E2, enprostil, given on three occasions shortly prior to a single exposure to 600 cGy external abdominal irradiation, on intestinal active and passive transport processes and villus morphology measured 7 days later. Animals were sham-irradiated (CONT) or were exposed to a single dose of 600 cGy external abdominal irradiation (RAD); two and one mornings before the day of irradiation or sham irradiation, and 1 h before irradiation or sham irradiation enprostil was administered. One half of CONT and RAD groups were dosed orally with enprostil, 5 micrograms/kg body weight, and the other half of the CONT and RAD groups were dosed with placebo. Seven days later the in vitro uptake of glucose, galactose, long-chain fatty acids, and cholesterol was determined in the four groups (CONT with and without enprostil, and RAD with and without enprostil). In CONT, enprostil was associated with increased jejunal uptake of glucose and ileal uptake of galactose. In RAD given enprostil, there was increased jejunal uptake of galactose but reduced ileal uptake of glucose and galactose. The expected radiation-associated decline in jejunal galactose uptake was prevented with enprostil. In CONT given enprostil, there was increased jejunal uptake of fatty acid (FA) 14:0 and 16:0 but reduced uptake of FA 18:0, 18:1, and 18:2; enprostil had no effect on lipid uptake in the ileum in CONT.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Saturated fatty acid diet prevents radiation-associated decline in intestinal uptake.

Adult female Sprague-Dawley rats were fed isocaloric semipurified diets containing a high content of either polyunsaturated (P) or saturated (S) fatty acids; these diets were nutritionally adequate, providing for all known essential nutrient requirements. On day 3 after beginning S or P, one group of animals was exposed to a single 6-Gy dose of abdominal radiation, and the other half was sham irradiated. S or P diets were continued for a further 14 days. Brush-border membrane purification and sucrase-specific activities were unaffected by diet or by abdominal irradiation. In rats fed P, irradiation was associated with an increase in jejunal brush-border membrane total phospholipid and the ratio of phospholipid to cholesterol; these changes were not observed in animals fed S. In irradiated rats, ileal brush-border membrane phospholipid per cholesterol was high in animals fed S compared with P. In irradiated animals fed P, there was reduced jejunal and ileal uptake of several medium- and long-chain saturated and unsaturated fatty acids and cholesterol, and the ileal uptake of higher concentrations of glucose was reduced in irradiated animals fed P. In contrast, lipid uptake was similar in control and irradiated animals fed S except for cholesterol uptake, which was reduced. Ileal uptake of higher concentrations of glucose was increased in irradiated animals fed S. Quantitative autoradiography failed to demonstrate any change in the distribution of leucine or lysine transport sites along the villus 1 or 2 wk after abdominal irradiation or in response to feeding S or P. Also, these differences in transport achieved by feeding S to radiated animals were not explained by variations in the animals' food consumption or intestinal mucosal surface area. Thus the use of short-term feeding with a saturated fatty acid diet in the prevention of acute irradiation damage to the intestine warrants further investigation in humans.

Amino Acids↗
PubMed1989

Invasion. A hospital in transition following the 1983 Grenadian intervention.

Stress, confusion, and a sense of loss were inevitable during the hospital relocation, especially given the large number of clients, ward communities, and staff needed to move and adjust to change. Despite the fact that the change was perceived as a positive and progressive step in psychiatric-mental health care in Grenada, there were many obstacles and much resistance to overcome. As expected, staff's and clients' fears centered around themes of impending loss and abandonment. An understanding of the transition process, along with the availability of experienced hospital staff for support and guidance, greatly aided the relocation process. Relocation still presented problems and Mt. Gay Hospital continues to struggle to carry out the lasting and beneficial changes that will best promote a therapeutic and culturally sensitive client/staff environment. Despite the fact that the hospital relocation was not entirely self-determined, but partially imposed by political circumstances, a positive resolution of the crisis occurred. The crisis brought about the change that, in this circumstance, is seen as synonymous with growth. It acted as a catalyst to bring about help from unexpected and much needed sources (U.S.A.I.D./Project Hope), which may not have otherwise been available to facilitate such a change. Richmond Hill Mental Hospital took control and advantage of a crisis situation and made it serve its immediate and pressing need for a new psychiatric hospital.

Adaptation, Psychological↗